Obesity and Diabetes

There’s a common definition of the word “obese”. We think of people who are really fat as being obese. I was one of them. 

What is Obesity?

Obesity has a technical definition which is somewhat arbitrary. It is a function of weight and height and is known as BMI (Body Mass Index). The US government definition is (NCHS Data Brief ■ No. 288 ■ October 2017):

Obesity: BMI was calculated as weight in kilograms divided by height in meters squared, rounded to one decimal place.

Obesity in adults was defined as a BMI of greater than or equal to 30.

BMI Weaknesses as a Metric

BMI (and obesity) does not take into account body composition such as body fat or lean body mass.  Two people can have the same BMI and be technically obese and one be solid muscle with little body fat and the other have significantly more body fat.

However, for the “average” person BMI is a decent measurement of fatness.

Obesity and Health

Generally, obesity and health are inversely related but there are people who are obese (by BMI) but are healthy. There are also people who are not obese but have poor health. This observation has led to the concept of personal fat threshold (PFT). This is described in (Taylor R, Holman RR.  Normal weight individuals who develop type 2 diabetes: the personal fat threshold. Clin Sci (Lond). 2015 Apr;128(7):405-10) (PDF).

Personal Fat Threshold (PFT)

The Personal Fat Threshold concept is that there’s a level of fatness which the individual can tolerate before their health is impacted. This concept is tempting but has some problems.

PFT is not all that useful in the a-priori sense. There is no objective test to see if someone is at or near their PFT. Obesity isn’t useful as a metric. Neither is body fat level.

The only use of PFT is to support the medical advice to patients of weight loss as a tool for management of Type 2 diabetes. The PFT concept doesn’t actually contribute much since it has been believed (before the PFT concept was developed) that weight loss of about 15% resolves diabetes (Reversing Diabetes with Weight Loss: Stronger Evidence, Bigger Payoff).

Until there’s an a-priori means of measuring PFT the approach seems to be not all that useful. No medical doctor can tell you that you are 10 lbs away from your PFT. The point is completely hidden until it manifests. All it says that is if you are not technically considered to be obese and you are diabetic it is because you have gone over your personal fat threshold. 

PFT – My Own Experience

There are three lines of reasoning from my own experience that call into question the PFT theory.

One was from my own experience with Insulin as a Type 2 Diabetic. I put on 40 lbs in a short time when I was put on Insulin. Conversely, when I got off Insulin my weight dropped quickly. Teenage females who are Type 1 diabetics and want to lose weight are well aware of this relationship. Weight increases followed Insulin increases (Skovsø S, Damgaard J, Fels JJ, Olsen GS, Wolf XA, Rolin B, Holst JJ. Effects of insulin therapy on weight gain and fat distribution in the HF/HS-STZ rat model of type 2 diabetes. Int J Obes (Lond). 2015 Oct;39(10):1531-8). not Insulin followed weight. Eventually, stasis is reached in weight and Insulin amount – at least in the short term.

Increasing dietary carbohydrates requires pumping more Insulin. When you stop eating dietary carbohydrates you don’t have to inject extra insulin for the meal. 

The second reason was the increase in Insulin that is required over time to maintain blood sugar levels. I started at about 40g of Insulin and had good blood sugar controls. By four later my weight was stable but the amount of Insulin to keep blood sugar stable kept increasing to about 120 units. More particularly, the amount of insulin to cover carbohydrate loads increased. In my own case 1 unit of Insulin could cover 15 grams of carbs when I started Insulin and by four years later 1 unit wasn’t enough to cover 8 grams. All of this was at a stable weight (after the initial gain) and the same level of carbohydrates.

A third reason is my own weight history. I was at 285 lbs and non-diabetic for years. Then I mysteriously lost 50 lbs down to 235 lbs over the course of about six months. This is a common occurrence with Type 2 diabetics (Unexplained Weight Loss and Diabetes). After six months of this unexplained weight loss, I was then diagnosed with diabetes.

Perhaps this is the body pushing back from the PFT but it does call the concept into question – or at least indicate the real issue is much more complicated. After being put on Metformin my weight stabilized at around 10 lbs higher (although Metformin is said to lower weight). As my diabetes got worse my doctor tried different medications some of which added weight and some (like Byetta) caused small weight loss. Finally, the addition of Insulin added 40 lbs to my weight.

I did low carb while on Insulin but it only took my HbA1C down to 6.4. It wasn’t until I did low carb plus Intermittent Fasting that I was able to get off Insulin and my weight fell very quickly. My last HbA1C was 5.2 which is a normal non-diabetic number.

Carbohydrate Insulin Relationship

At the very least, if the PFT concept is salvageable, it needs to be modified for increasing Insulin Resistance levels. If the best treatment for diabetes is weight loss the best way for Type 2 Diabetics to lose weight is to reduce insulin levels. The best way to reduce insulin levels is to the insulin load of the diet. For a Type 2 Diabetic who is on Insulin this results in a loss of a lot of weight in a very short period of time.

The recommendation that losing 15% of body weight does not seem plausible to a diabetic like myself. I’ve lost more than 15% from my peak weight and not been able to control my diabetes. I lost weight with Low Carb by itself but not enough to get off Insulin. At it was more than 15% of weight loss.  If I was told that losing 15% of my body weight would control my diabetes I would have told my doctor that I tried it and it didn’t work.

I lost much less than 15% of my weight in the beginning of Low Carb plus Intermittent Fasting and was able to get off Insulin completely. It was getting off Insulin which allowed me to lose weight. And it was reducing my body’s Insulin needs by the Low Carb diet and Intermittent Fasting which worked for me.

See (Obesity and Insulin Resistance).

Low Carb Hypothesis

Low Carb diets often result in greater weight loss than low fat diets – this BLOG has linked to many of these studies.

One explanation hypothesized for the greater weight loss on Low Carb diets is the Low Carb diet is said to have an inherent metabolic advantage. This metabolic advantage should manifest itself in a greater resting energy expenditure. The paper looked at two possible mechanisms – triglyceride cycling and glyceroneogenesis.

The critics of the Low Carb diet say that the advantage is that the comparisons aren’t done by holding protein constant. Overfeeding protein is not the same as overfeeding carbs or fat since protein stimulates 24 hour energy expenditure and fat doesn’t (Overfeeding Protein – Carnivore Diet).

Look to the Science

A short term (6 weeks) small (4 subjects) study was done on obese women to compare the Low Carb and Low Fat diets which held energy (total calories) and protein constant ( Segal-Isaacson CJ, Johnson S, Tomuta V, Cowell B, Stein DT. A randomized trial comparing low-fat and low-carbohydrate diets matched for energy and protein. Obes Res. 2004 Nov;12 Suppl 2:130S-40S). The study concluded that there is no significant differences when controlling for protein.

Our results showed no significant weight loss, lipid, serum insulin, or glucose differences between the two diets. 

The study was a decently formulated study but there were weaknesses:

  • Small study – only 4 subjects
  • No control group
  • Older obese females only
  • Very short duration (6 weeks)
  • Low fat didn’t get super-low (20% of calories from fat)
  • The Low Carb diet results in more weight loss but the study was too small to have statistical power

The good parts of the study were:

  • Controlled feeding
  • Matched total calories and protein – varying carbs and protein
  • Decent protein level (30% of calories)
  • Low carb was 5% of calories – good level
  • Randomized control trial
  • Cross-over design so the subjects ate both foods in random order
  • Starches and fruit were the carbohydrate choices (not jelly beans)
  • Deficit was relatively small (200 calories below REE which is a fairly large amount below TDEE depending on activity level)

At the end of the study they gave the participants the choice to continue on for a year. They were given the choice of the two diets and three of the four participants chose the Low Carb diet. However, the Low Carb participants raised their carbohydrate amount from 5% to 23% over the rest of the study so their weight loss partially reversed. There were several distinct advantages for the Low Carb diet.

Lipids were dramatically reduced on both diets, with a trend for greater triglyceride reduction on the VLC diet. Glucose levels were also reduced on both diets, with a trend for insulin reduction on the VLC diet

This fits my own experiences with protein and Low Carb. I’ve seen people stall for a long time and then break the stall by increasing their protein (and dropping their fat). My conclusion is that the ketogenic diet advantage does come from the higher protein intake of the diet. The diet often causes people to increase their consumption of meat which a high quality food.

Just Eat More Protein?

Protein alone doesn’t produce the same advantage that protein and Low Carb have together. This is shown in studies which substitute carbohydrates for protein (Blatt AD, Roe LS, Rolls BJ. Increasing the protein content of meals and its effect on daily energy intake. Journal of the American Dietetic Association. 2011;111(2):290-294).

This study showed that varying the protein content of several entrées consumed ad libitum did not differentially influence energy intake or affect ratings of satiety over a day. When the appearance, taste, fat content, and energy density were controlled, simply adding meat to lunch and dinner entrées to increase the protein content within commonly consumed amounts was not an effective strategy to reduce daily energy intake.

Sigma Nutrition Radio

Here’s a good program on this subject (SNR #64: Are Low-Carb Diets More Effective For Fat Loss?). tl/dl – Low Carb probably has better adherence than Low Fat diets.

Evidence for the Role of Insulin in Weight Gain

Here’s an interesting study which provides evidence for the role of Insulin in Weight Gain (Velasquez-Mieyer P, Cowan P, Arheart K, et al. Suppression of insulin secretion is associated with weight loss and altered macronutrient intake and preference in a subset of obese adults. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 2003;27(2):219-226).

For the entire cohort, significant insulin suppression was achieved with simultaneous improvements in insulin sensitivity, weight loss, and body mass index (BMI). Leptin, fat mass, total caloric intake, and carbohydrate craving significantly decreased.

When grouped by BMI response, high responders (HR; ΔBMI < −3 kg/m2) and low responders (LR; ΔBMI between −3 and −0.5) exhibited higher suppression of CIRgp and IAUC than nonresponders (NR; ΔBMI > −0.5). CISI improved and significant declines in leptin and fat mass occurred only in HR and LR.

Conversely, both leptin and fat mass increased in NR. Carbohydrate intake was markedly suppressed in HR only, while carbohydrate-craving scores decreased in HR and LR. For the entire cohort, ΔBMI correlated with ΔCISI, Δfat mass, and Δleptin. ΔFat mass also correlated with ΔIAUC and ΔCISI.

In a subcohort of obese adults, suppression of insulin secretion was associated with loss of body weight and fat mass and with concomitant modulation of caloric intake and macronutrient preference.

From the body of the study:

The role of increased carbohydrate craving and intake has been previously suggested to play a contributory role in the development of obesity. However, the connection between insulin and carbohydrate craving and intake is less clear. The frequent intake of highly refined carbohydrates may induce weight gain by initiating and sustaining a chronic state of hyperinsulinemia. Carbohydrate intake stimulates insulin secretion, raising circulating insulin levels, which in turn favors increased fatty acid uptake, lipid biosynthesis, and inhibition of lipolysis, leading to energy storage.

Conversely, it had been suggested that insulin stimulates hyperphagia and fosters carbohydrate cravings, producing increased levels of insulin that promote insulin resistance and exacerbation of the hyperinsulinemic condition. This suggests that a vicious cycle is set in motion that perpetuates hyperinsulinemia and weight gain, and that breaking this cycle can promote weight loss.

Interesting.

Carbs are Fat Sparing

Our bodies burn carbs in preference to fats. That is because we only have a limited amount of storage for carbs and we have a very high capacity for fat storage. 

We are typically burning some mixture of both fat and carbs (except at extremes). The amount of carbs we are burning is strongly influenced by the amount of carbs we have eaten. If you ate nothing but carbs and ate them at an amount matching your total energy expenditure you will pretty much just burn carbs. 

Since most people don’t eat in their sleep there’s some point where the carbs go down and the body starts to draw from the carb stores, aka, glycogen. That can last as long as a day or so but as the glycogen stores draw down the body starts to shift to fat burning. This is known as glycogen sparing.

On a low carb diet our fuel mixture shifts to largely fat based. At very low levels of Insulin that come with a reduction in carbohydrates, our peripheral cells resist the small amount of glucose we produce and we spare the glucose for the parts of our body which rely on glucose for fuel. This is how the low carbohydrate diet is glucose/glycogen sparing.

A high carb diet is fat sparing since it spares our body fat from being burned and reduces the amount of time that glycogen stores are being drawn down. 

Diabetes and Weight Loss

A typical explanation for those of us who reversed our diabetes is that we did so because we lost weight. That can be found in a quite a few places like this (Nicola D. Guess. Dietary Interventions for the Prevention of Type 2 Diabetes in High-Risk Groups: Current State of Evidence and Future Research Needs. Nutrients 2018, 10(9), 1245).

Weight loss appears to be the primary driver of type 2 diabetes risk reduction, with individual dietary components playing a minor role. 

I don’t buy it. I got off Insulin in two weeks. Can it be based on weight loss? I don’t believe so. The reason is that I was diabetic over a wide range of weights – from the 230’s into the 280’s. At the time I went on LCHF + IF I was at 285. I didn’t drop below 230 in two weeks. Here is my weight loss chart. 

Blood Sugar Roller Coaster – Part 2

A good small study comparing the blood sugar and insulin responses to breakfasts with different fat/carb/protein values at the same number of calories (Paula C. Chandler-Laney, et.al. Return of hunger following a relatively high carbohydrate breakfast is associated with earlier recorded glucose peak and nadir. Appetite. Volume 80, 1 September 2014, Pages 236-241).

Turns out that a Low Carb High Fat breakfast results in a lower Area Under the Curve (AUC) for Insulin and higher blood sugar levels hours after breakfast. The lower AUC makes sense since there’s less glycemic load from lower carbohydrates. However, the glucose response may be counter-intuitive. It happens because the problem with higher glucose in meals is a larger drop in glucose after the meal digests. Eating lower carbs results in less of a drop in blood sugar. And it also results in less hunger.

The study protocol was:

Overweight but otherwise healthy adults (n = 64) were maintained on one of two eucaloric diets: high carbohydrate/low fat (HC/LF; 55:27:18% kcals from carbohydrate:fat:protein) versuslow carbohydrate/high fat (LC/HF; 43:39:18% kcals from carbohydrate:fat:protein). After 4 weeks of acclimation to the diets, participants underwent a meal test during which circulating glucose and insulin and self-reported hunger and fullness, were measured before and after consumption of breakfast from their assigned diets.

The results of the study were:

The LC/HF meal resulted in a later time at the highest and lowest recorded glucose, higher glucose concentrations at 3 and 4 hours post meal, and lower insulin incremental area under the curve.

Participants consuming the LC/HF meal reported lower appetite 3 and 4 hours following the meal, a response that was associated with the timing of the highest and lowest recorded glucose.

Credit to Ted Naimam for pointing out this study.

Low Carb vs Reduced Calorie

An interesting study that took a look at an ad libitum Low Carb diet compared to a Low Calorie diet (Foster, Gary D. et.al. A Randomized Trial of a Low-Carbohydrate Diet for Obesity. New England Journal of Medicine, 2003, VI 348, pp 2082-2090). The groups were:

We conducted a one-year, multicenter, randomized, controlled trial to evaluate the effect of the low-carbohydrate, high-protein, high-fat Atkins diet on weight loss and risk factors for coronary heart disease in obese persons. The subjects were randomly assigned to follow either a low-carbohydrate, high-protein, high-fat Atkins diet or a high-carbohydrate, low-fat, energy-deficit conventional diet.

The Low Calorie group was pretty restrictive:

1200 to 1500 kcal per day for women and 1500 to 1800 kcal per day for men, with approximately 60 percent of calories from carbohydrate, 25 percent from fat, and 15 percent from protein

You’d think that with the Low Carb group able to eat what they want that the calorie restricted group would beat them hands down. The results were:

Subjects on the low-carbohydrate diet had lost more weight than subjects on the conventional diet at 3 months (mean [±SD], –6.8±5.0 vs. –2.7±3.7 percent of body weight; P=0.001) and 6 months (–7.0±6.5 vs. –3.2±5.6 percent of body weight, P=0.02), but the difference at 12 months was not significant (–4.4±6.7 vs. –2.5±6.3 percent of body weight, P=0.26). After three months, no significant differences were found between the groups in total or low-density lipoprotein cholesterol concentrations. The increase in high-density lipoprotein cholesterol concentrations and the decrease in triglyceride concentrations were greater among subjects on the low-carbohydrate diet than among those on the conventional diet throughout most of the study. Both diets significantly decreased diastolic blood pressure and the insulin response to an oral glucose load.

Carb-Insulin Theory

There’s a lot of contention about the carbohydrate-insulin-obesity (C-I-O) hypothesis to explain obesity. In my opinion, some of this can be traced to Gary Taubes’ abrasive personality. Gary is someone that a lot of people love to hate and he seems to like to help them hate him (Gary Taubes BLOG on this subject).

One of the leading voices against C-I-O is Stephan Guyenet. His BLOG frequently takes on Gary Taubes and the C-I-O hypothesis. In this post he takes on one of the more reputable proponents of C-I-O (Testing the Insulin Model: A Response to Dr. Ludwig. Saturday, January 30, 2016).

Gary Taubes’ main objection is to the Calories-In-Calories-Out (CICO) model. Stephen Guyenet isn’t a supporter of CICO but he sees Taubes’ objections as against a caricatured strawman. Guyenet recognizes the weakness of the CICO model. One of his more salient points is:

This [CICO] model seems to exist mostly to make lean people feel smug, since it attributes their leanness entirely to wise voluntary decisions and a strong character.

Stephen provides a critique of the Carb-Insulin hypothesis that lists a large number of studies that provide evidence against the predictions that the C-I-O hypothesis generates.

I will take some time in the future to look at his lines of evidence against C-I-O but my own interest in Low Carb was from the effect on T2 diabetes and not so much in obesity. Weight loss is just a nice side effect of Low Carb. I have struggled more with Low Carb to reach maintenance than I have with weight loss. I have no doubt that Low Carb works well for Type 2 diabetes. Whether or not the issue is the hormone Insulin or some other cause matters less to me than the effect. I think the evidence is that Low Carb does a better job at managing T2D without medications than either the Zone or Paleo diets.

Stephen’s Model of Obesity

Stephen goes on to presents a third model to answer the basic questions.

This model centers around Leptin and Insulin and places the brain at the center of weight control. Stephen presents his view in this paper (Stephan J. Guyenet and Michael W. Schwartz. Clinical Review. Regulation of Food Intake, Energy Balance, and Body Fat Mass: Implications for the Pathogenesis and Treatment of Obesity. J Clin Endocrinol Metab. 2012 Mar; 97(3): 745–755). From the paper:

The increase of energy intake that has fueled the U.S. obesity epidemic is linked to greater availability of highly rewarding/palatable and energy-dense food.

Obesity occurs in genetically susceptible individuals and involves the biological defense of an elevated body fat mass, which may result in part from interactions between brain reward and homeostatic circuits.

Inflammatory signaling, accumulation of lipid metabolites, or other mechanisms that impair hypothalamic neurons may also contribute to the development of obesity and offer a plausible mechanism to explain the biological defense of elevated body fat mass.

This is where Low Carb can work well since it eliminates these highly palatable food. However, Stephen doesn’t see a particular advantage to Low Carbohydrate diets.

Among various scientific rationales that have been advanced for such diets is that excessive insulin secretion induced by rapidly digested carbohydrate foods causes a subsequent, transient fall of plasma glucose levels; this, in turn, triggers excess feeding and ultimately causes obesity. …. Although clinical trials have established that reduced carbohydrate diets can safely induce modest long-term weight loss, the mechanisms typically advanced to explain this benefit have little in the way of experimental support and are not informative with respect to the control of food intake.

I think there’s something to the fall of blood sugar stimulating hunger. The reason I think that’s true is that it is my experience. I get hungry a few hours after eating a protein meal. Stephen’s explanation is that it is because my stomach is emptying and sending a signal to the brain. It would be interesting to note the difference in someone with a different reaction to protein meals. This theory is old and is presented here (Jean Mayer. Glucostatic Mechanism of Regulation of Food Intake. N Engl J Med 1953; 249:13-16).

Protein Dilution Theory

An alternate explanation of the data is the Protein Leverage Hypothesis. The increase in obesity is explained by an increase in food consumption since 1980 which matched a relatively stable absolute level of protein in the diet. If the total calories are going up but the protein calories are constant it means that the protein is being diluted. The theory is that we seek out a constant level of protein which means we need to eat more food to get our protein if the protein content of food is decreasing. Ted Naiman states this as (Diet 2.0 – Homo sapiens diet):

Today, modern agricultural practices and modern food processing have dumped a massive quantity of refined carbohydrates (sugar and flour) and refined fats (oils) into the food supply, creating protein and nutrient dilution. Because humans eat to a tightly regulated protein and micronutrient satiety drive, we frequently overeat empty calorie carbs and fats just to get adequate protein and micronutrients.

Ludwig’s Latest Paper

Ludwig produced a paper recently ( Ludwig David S, et.al. The Carbohydrate-Insulin Model of Obesity: Beyond “Calories In, Calories Out”
JAMA Intern Med. 2018 Aug 1;178(8):1098-1103).

See Ludwig’s earlier response to Guyunet (Defense of the Carbohydrate-Insulin Model Redux: A Response to Kevin Hall).

Our Cousin Paleo

The Paleo diet is a close cousin to the Low Carb diet. The Paleo and Low Carb diets are both elimination diets (they say to not eat particular things) and many of the things that they eliminate are in common.

The Paleo diet is based on the idea that our genetics were formed in the Paleolithic Period. This is the time period before agriculture. Man was largely a hunter/gatherer in our long developing history. Thus, the Paleo diet eliminates grains since they are largely the product of agriculture. The Low Carb diet also eliminates grains but it is because they are concentrated forms of carbohydrates.

Paleo as a Philosophy

Paleo is based on an ancestral/evolutionary philosophy. The idea is that man has developed over millions of years. Natural selection is the process which has eliminated and honed man down to the specific biological machines that we are. Eating food which was consistent with what we ate over that long period makes more sense than eating Fruit Loops. 

The Biblical story is often placed in contrast to this point of view. In the Bible Adam and Eve are placed into a garden to tend the garden. There are indications in the text that the original order was not consuming animal products. After the flood story man is told Noah is to eat animals.

The human earliest conflict in the Bible is between the brothers Cain and Abel – farmer and a herdsman. The farmer brings a sacrifice from his crops and God is displeased. The herdsman slaughters an animal and his sacrifice pleases God. Thus, the evidence in the Bible is that both are very early modes.

Processed Foods

For either the evolutionary or Biblical view, processed food is very recent in our history. We are not well adapted to these processed foods. Eating natural foods fits well into either paradigm. The wheat/bread in Bible times is not like our flour/Wonder Bread products of today. The refining process eliminates protective elements, like fiber, from the raw food.

Refining/processing concentrates carbohydrates into a more dense form. Imagine something like fudge in nature – you can’t find an equivalent thing. The only really sweet things in nature, like honey are pretty well protected. Even sugar cane is fairly low in sugar. It’s when it is processed into powder form that it becomes dense and separated from fiber.

Studies have been done which show good results with Paleo diets (Tommy Jönsson. A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs. Nutrition & Metabolism, 2006;Nov 2, v3.1,  p 39).

This study in domestic pigs suggests that a Paleolithic diet conferred higher insulin sensitivity, lower C-reactive protein and lower blood pressure when compared to a cereal based diet.

Not that we want skinny pigs.

Paleo Mortality

The issue of life expectancy is given as an argument against the Paleo diet. After all cavemen, they say, died at early ages. Much of the reason for early death is due to accident or bacterial infection. There is evidence that there was very little heart disease in our Paleolithic ancestors.

Storage in Man vs Storage in Structures

Man has a very limited ability to store carbohydrates directly in the body. We store dietary carbohydrates in the form of glycogen which we have about a day’s worth of stores. Excessive protein, carbohydrates and fat get stored in our body which can take us through many weeks/months of food shortage. It is rare in our world to face extended shortages of food. Even our poor are rarely hungry.

Animal products are quickly perishable and refrigeration is a relatively new invention which extends this time. Carbohydrates, in the form of grains, can be stored for very long times.

It is interesting that the ability of our bodies to store food is the opposite of the storage capabilities of food. After agriculture came into prominence, wheat got more people through famines.

Dairy is a Difference

Paleo typically doesn’t include dairy products (THE PLACE OF DAIRY ON A PALEO DIET). Low Carb diets typically include dairy although some people find the high fat nature of dairy products can slow weight loss.

Fruit is a Difference

The Paleo diet includes fruit. A possible criticism of some implementations of the Paleo diet is that Paleolithic man would have only had access to fruit in short seasons and in limited forms. It is noteworthy that the more north the less fruits are available both in variety and season length.

My raspberry bush produces black raspberries every year. The entire plant provides a very limited number of berries. I can’t practically access most of the berries since the plant has barbs that protect many of the berries. For some reason bugs don’t bother the plant. I eat the berries when they come in season and I will eat all of the berries I can harvest from my one very large plant. I eat them every day or two. It’s not all that many grams of carbs total and they taste great. But the season when the berries are there is really short here in SW PA. There’s large seeds in the berries and probably a good amount of fiber. It takes 4 ozs of the berries to get 17g of carbohydrates and I never get anywhere near that much in a single day (Nutritional Value of Black Raspberries). I don’t know if this is a natural plant or one that someone deliberately planted in the past. It’s in the corner of my backyard.

The exception to seasonal limits may be tropical regions where food like bananas have been more widely available over wider time frames (Banana Tree Harvesting – Learn How And When To Pick Bananas). To make the point though, bananas just entered the North American diet after the Civil War (Wikipedia). It hasn’t been long in terms of our history that we could get bananas any day of the week and for a couple of pounds per dollar and bananas certainly weren’t a part of my own Northern European ancestry.

The Low Carb diet eliminates nearly all fruit due to the high carbohydrate load. There is no accommodation for seasonality in Low Carb.

Paleo/Low Carb Hybrid

Both sides have learned from each other. It is possible to eat Low Glycemic foods on Paleo. The Low Carb community has taken some of the criticisms about excess fat consumption from the Paleo community. Some Low Carb folks have found dairy to be problematic and adopted a hybrid approach to their diet. 

“But Kitavas Eat Sweet Potatoes”

One of the common rebuttals to the Carbohydrates + Insulin => Obesity hypothesis is the case of the Kitavans (Lindeberg S, Nilsson-Ehle P, Terént A, Vessby B, Scherstén B. Cardiovascular risk factors in a Melanesian population apparently free from stroke and ischaemic heart disease: the Kitava study. J Intern Med. 1994 Sep;236(3):331-40). The Kitavans eat ancestral diets with huge amounts of carbohydrates, mainly sweet potatoes.

Low Caloric Density

Part of the answer may be found in the caloric density of Sweet Potatoes. Turns out not it takes a whole lot of potatoes to get in your daily calories. 

One pound of Sweet Potatoes provides 340 calories. The typical Kitavan’s energy expenditure was measured at 2200 calories. To get in 2200 calories in a day that would be more than 6 lbs of Sweet Potatoes. That’s a lot of Sweet Potatoes.

Plus, if you could manage to eat 6 lbs of Sweet Potatoes a day it would only be ~40g of protein over the whole day.

Low Fat Choice

It is also a very low fat choice with 4.4g of fat in the 7 lbs of Sweet Potatoes. It is theoretically possible to be lean on very high carbohydrates but you have to be very low fat at the same time.

This diet isn’t the typical hyper-palatable diet of the west. 

Serum Fasting Insulin Differences

As noted, the Kitavan diet is a common rebuttal to the Carbohydrate Insulin Obesity hypothesis. However, the insulin levels of the Kitavans show that they have much lower fasting insulin levels than Europeans (Lindeberg, Staffan et al. Low serum insulin in traditional pacific islanders—The Kitava study.  Metabolism – Clinical and Experimental , Volume 48 , Issue 10 , 1216 – 1219).

Serum fasting insulin levels were lower in Kitava than in Sweden for all ages (P < .001). For example, the mean insulin concentration in 50- to 74-year-old Kitavans was only 50% of that in Swedish subjects. Furthermore, serum insulin decreased with age in Kitava, while it increased in Sweden in subjects over 50 years of age. Moreover, the age, BMI, and, in females, waist circumference predicted Kitavan insulin levels at age 50 to 74 years remarkably well when applied to multiple linear regression equations defined to predict the levels in Sweden. The low serum insulin that decreases with age in Kitavans adds to the evidence that a Western lifestyle is a primary cause of insulin resistance. 

At best, then, it could be claimed that it is possible to have a low fasting insulin and a relatively high carbohydrate diet and the link of carbohydrates to fasting insulin levels is a central claim of the carbohydrate insulin obesity hypothesis.

Other Dietary Differences

Kitavans also eat a significant amount of fish. There are quite a few other interesting facts about the Kitavan diet (See: Interview with a Kitavan).

The Kitavans eat no grains. Their diet has a lot of tubers.

Seasonality

The Kitavans eat different starchy carbohydrate sources throughout the year. From the Interview above:

In the beginning of the year, we eat sweet potato, cassava and mostly tuna for protein. During mid year, before yam comes in to replace sweet potato and cassava, taro is then ready for harvest. And then yams are ready for harvesting so the food supply is continued on.

Lot of Smokers

An interesting tidbit is that 75% of the Kitavans are smokers and yet they have little to no heart disease. Does that mean we should take up smoking?

More Speculation and Differences

Interesting paper on the subject (Ian Spreadbury. Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity. Diabetes Metab Syndr Obes. 2012; 5: 175–189).

A diet of grain-free whole foods with carbohydrate from cellular tubers, leaves, and fruits may produce a gastrointestinal microbiota consistent with our evolutionary condition, potentially explaining the exceptional macronutrient-independent metabolic health of non-Westernized populations, and the apparent efficacy of the modern “Paleolithic” diet on satiety and metabolism.